Search Results (33)

Objective: To examine lower-body stretch–shortening cycle (SSC) indicators across chronological age categories and playing positions in elite male youth soccer players. Methods: In a cross-sectional design, 984 male players from Slovakia (U15–U19) completed Squat Jumps (SJ), Countermovement Jumps (CMJ), and Drop Jumps (DJ) using the OptoJump photocell system. Outcomes included Eccentric Utilization Ratio (EUR), Reactive Strength Index (RSI), DJ Ground Contact Time (DJ GCT), and Jump Heights (JH). Differences were tested using factorial ANCOVA (age category × playing position) adjusted for height and weight, followed by Tukey-adjusted post hoc comparisons (p < 0.05). Results: Significant age-category main effects were observed for DJ RSI, DJ JH, CMJ JH, SJ JH, and DJ GCT. The largest effects were for DJ JH, CMJ JH, and SJ JH (ηp² = 0.096–0.112), whereas the DJ GCT effect was statistically significant but small (ηp² = 0.013). EUR showed no significant differences across age categories (p = 0.586). Positional differences were limited overall and mainly evident in selected U19 outcomes, particularly jump-height variables and DJ GCT. Conclusions: Lower-body SSC performance increased across chronological age categories, with the largest separation in jump-height and reactive strength outcomes. These differences likely reflect a combination of maturation, training exposure, and selection rather than chronological age alone. EUR remained stable across age categories and playing positions, although the JH-based ratio has limited sensitivity in the present test configuration. Positional separation emerged mainly at U19, supporting broad SSC development across earlier youth categories and position-sensitive interpretation in the oldest cohort. Full article

Inertial measurement units (IMUs) present promising avenues for performance diagnostics in skateboarding, yet systematic validation of their accuracy and applicability remains limited. This study validates the commercially available Spinnax Freak IMU system in the context of skateboarding, with a focus on selected trick detection and classification, distance measurement, maximal horizontal speed, maximal vertical height of the skateboard and airtime during a jump trick. A total of 23 skateboarders (4 females, 19 males; 27.4 ± 10.9 years) participated in this study. Validation methods included comparisons with established reference systems such as laser ranging for maximal horizontal speed (LAVEG), 2D video analysis for maximal vertical height of the skateboard (Kinovea), light barrier measurements for airtime detection (OptoJump Next), and a fixed metric reference (10 m) for rolling distance measurements. The evaluation was supported by statistical analyses including mean absolute error (MAE), root mean-square error (RMSE), mean absolute percentage error (MAPE), t-tests, Bland–Altman plots, linear regression, and ICC(3,1). The Spinnax Freak system demonstrated high validity in detecting trick events and in providing distance measurements that were statistically equivalent to the reference. Trick classification, maximal horizontal speed, maximal vertical height of the skateboard and airtime showed substantial errors, indicating that these outputs are not reliable for biomechanical interpretation at this point. These findings highlight both the potential and the current constraints of single-sensor setups for field-based motion capture in skateboarding. Future developments should prioritize algorithmic refinement, improved temporal resolution, and optimized event classification to enhance measurement accuracy and expand applicability in biomechanical analysis and automated training documentation in skateboarding. Full article

Background: This study investigated how kinematic parameters vary during repeated 50 m sprints and their relationship with movement stability and hamstring injury risk among sprinters at different competitive levels. Methods: Eighteen male Polish National Team sprinters (nine elite, nine sub-elite) performed four 50 m sprints, with measurements of step length, frequency, ground contact time, and flight time taken using the OptoJumpNEXT system across the entire track. The fastest and slowest trials were analyzed, and a 26-question survey examined participants’ hamstring injury history and prevention strategies. Results: Results showed that elite sprinters posted faster times, higher step frequency, shorter ground contact times, and increased step velocity, indicating more stable, consistent sprint mechanics. About 89% of athletes reported previous hamstring injuries, mainly during the late swing phase or between 40 and 50 m. The highest injury rate occurred during the fourth repetition, highlighting fatigue as a key risk factor. Elite sprinters mainly increased speed through higher step frequency and shorter ground contact times, while sub-elite athletes relied more on longer step lengths. Conclusions: Overall, elite sprinters exhibit more stable and efficient movement patterns, which may reduce the risk of hamstring strain injury. In contrast, the greater variability and fatigue seen in sub-elite athletes could heighten their injury vulnerability. Full article

Background/Objectives: Running is among the most prevalent forms of physical activity in preschool-aged children and constitutes a fundamental component for the effective execution of other motor patterns. The main aim of this study is to determine how fundamental running parameters change with age and whether there are differences between sexes. Methods: Four-hundred and five pre-school children with the mean (SD) age = 4.9 (1.1) years, height = 111.2 (9.3) cm, weight = 20.0 (4.2) kg, 53.5% girls were recruited from 34 kindergartens in four major cities. The inclusion criteria involved children aged 3–6 years with typical development and without any locomotor or mental disorders and diseases, who were enrolled in day care. Running performance was assessed in preschool children using a 10-m sprint test. Sprint parameters were measured with the OptoJump modular system, an infrared platform that accurately quantifies kinematic variables. Sex (boys vs. girls) and age (3 to 6 years old) differences were calculated by using analysis of variance (ANOVA) or Kruskal–Wallis H-test with post hoc comparison test between the groups. Results: In general, the results indicated that statistically significant differences between boys and girls were observed across the following levels: (1) temporal–kinematic step phase, (2) spatiotemporal movement characteristics, and (3) propulsive phase as an indicator of muscular activity. However, these differences were not consistent across all age groups. Conclusions: This study provides new insights into the spatiotemporal characteristics of running in preschool-aged children. The findings may assist in the early identification of potential motor deviations and in the planning of more effective strategies to promote physical activity during the preschool period. Full article

This study investigates the effects of a structured motor intervention program on the development of lower limb strength in junior athletes practicing Greco-Roman wrestling. Recognizing the crucial role of explosive strength in performing technical and decisive actions during combat, the research introduces a progressive, applied training protocol tailored to the neuromotor development of children aged 10 to 12 years (control group: M = 11.14, SD = 1.10; experimental group: M = 11.07, SD = 0.83). Conducted over 17 months, the study involved two groups of 14 registered wrestlers each from School Sports Club No. 5 in Bucharest. The experimental group participated in a complementary motor training program emphasizing plyometric drills, bodyweight strength exercises, and wrestling-specific movements, while the control group continued with the standard training routine. The intervention’s impact was evaluated using the OptoJump Next system, a biomechanical analysis tool measuring key indicators of explosive strength—jump height, ground contact time, flight time, and reactive strength index (RSI)—through the single-leg counter-movement jump (CMJ) test. Comparative analysis of pre- and post-intervention results showed significant improvements in neuromotor performance among athletes in the experimental group, confirming the effectiveness of the proposed methodology. This research thus provides a reproducible, evidence-based intervention model with direct applicability in optimizing the training of young Greco-Roman wrestlers. Full article

Vertical jumping is a fundamental motor skill that develops rapidly in early childhood, yet the biomechanical contribution of arm swing in preschool-aged children remains unclear. This study aimed to investigate how arm swing influences countermovement jump (CMJ) performance in typically developing children aged 3 to 6 years. A total of 411 children (53.5% girls; mean age: 4.9 ± 1.1 years) from four European cities participated in this cross-sectional study. Each child completed five CMJs with and without arm swing using the Optojump system, measuring variables such as jump height, flight time, contact time, power, the reactive strength index (RSI), pace, and verticality. The results revealed a significant increase in jump height when using arm swing for both boys (+15%) and girls (+12.5%) (p < 0.001), yet power output, the RSI, pace, and verticality decreased significantly (p < 0.05). These findings suggest that preschool children are not yet biomechanically efficient in integrating arm movements into vertical jumping due to immature neuromuscular coordination. Although arm swing improves jump height, it does not enhance overall movement efficiency at this developmental stage. This study highlights the need for multidimensional and age-appropriate assessment protocols to better understand motor integration during early childhood. Full article

Background: Repeated vertical jump tests are widely used to assess neuromuscular function and lower limb performance. However, inconsistent formulas for average power output produce large discrepancies, limiting comparability across studies and limiting practical applications. This study aimed to compare three different models for the calculation of average power output, Bosco, Miron Georgescu (MG), and Modified Miron Georgescu-15s (MGM-15), applied to identical jump test data, in order to evaluate their computational behavior and practical relevance in athlete performance profiling. Methods: A single-group quasi-experimental study was conducted with 25 physically active male university students (mean age: 21.4 ± 2.7 years), who performed a 15 s repeated vertical jump test on the OptoJump Next system. Raw parameters including flight time, contact time, and jump height were recorded and exported. Average power output (W/kg) was subsequently calculated using three distinct computational models, each applied to the same dataset of flight and contact times. A repeated-measures ANOVA was used to compare outputs across models, with Bonferroni-adjusted pairwise comparisons for post hoc analysis (α = 0.05). Results: Significant differences were observed (p < 0.001). The Bosco model produced the highest values of average power (40.13 ± 8.56 W/kg), followed by MG (21.07 ± 5.92 W/kg), while MGM-15 yielded the lowest and most consistent outputs (4.08 ± 0.61 W/kg). Effect sizes were very large (η²_p = 0.952), confirming that calculation models strongly influenced the outcomes. Conclusions: The findings demonstrate that average power output differed markedly across formulas, despite identical performance data. Bosco and MG models tended to overestimate values due to simplified assumptions, whereas the MGM-15 method produced lower and more consistent outputs that may better capture repeated jump demands. The standardization of computational models is fundamental to ensure comparability and to improve athlete performance profiling in research and practice. Full article

Aim: This study analyzed the concurrent validity of the Optojump infrared photocell system for estimating lower limb peak power by comparing it with the 15 s Wingate anaerobic test (WAnT) and examining relationships with sprint performance indicators. Methods: Twelve physically active university students (ten males, two females; age: 23.39 ± 1.47 years; body mass: 73.08 ± 9.19 kg; height: 173.67 ± 6.97 cm; BMI: 24.17 ± 1.48 kg·m⁻²) completed a cross-sectional validation protocol. Participants performed WAnT on a calibrated Monark ergometer (7.5% body weight for males, 5.5% for females), 30 s continuous jump tests using the Optojump system (Microgate, Italy), and 30 m sprint assessments with 10 m and 20 m split times. Peak power was expressed in absolute (W), relative (W·kg⁻¹), and allometric (W·kg^−0.67) terms. Results: Thirty-second continuous jump testing produced systematically higher peak power values across all metrics (p < 0.001). Mean differences indicated large effect sizes: relative power (Cohen’s d = 0.99; 18.263 ± 4.243 vs. 10.99 ± 1.58 W·kg⁻¹), absolute power (d = 0.86; 1381.71 ± 393.44 vs. 807.28 ± 175.45 W), and allometric power (d = 0.79). Strong correlations emerged between protocols, with absolute power showing the strongest association (r = 0.842, p < 0.001). Linear regression analysis revealed that 30 s continuous jump-derived measurements explained 71% of the variance in Wingate outcomes (R² = 0.710, p < 0.001). Sprint performance showed equivalent predictive capacity for both tests (Wingate: R² = 0.66; 30 s continuous jump: R² = 0.67). Conclusions: The Optojump infrared photocell system provides a valid and practical alternative to laboratory-based ergometry for assessing lower limb anaerobic power. While it systematically overestimates absolute values compared with the Wingate anaerobic test, its strong concurrent validity (r > 0.80), large effect sizes, and equivalent predictive ability for sprint performance (R² = 0.66–0.71) confirm its reliability as a field-based assessment tool. These findings underscore the importance of sport-specific, weight-bearing assessment technologies in modern sports biomechanics, providing coaches, practitioners, and clinicians with a feasible method for monitoring performance, talent identification, and training optimization. The results further suggest that Optojump-based protocols can bridge the gap between laboratory precision and ecological validity, supporting both athletic performance enhancement and injury prevention strategies. Full article

This study aimed to examine the validity and reliability of the AI-based DeepSport application by comparing its outcomes with those from the reference device, OptoJump. The primary dependent variables measured were jump height and anaerobic power during vertical jump assessments. Twelve elite male basketball players voluntarily participated in the study (age = 21.53 ± 1.14 years; sports experience = 6.47 ± 1.01 years). DeepSport uses AI-based image processing from standard cameras, while OptoJump uses optical sensor technology. Both DeepSport and OptoJump systems were utilized to assess participants’ Countermovement Jump (CMJ) and Squat Jump (SJ) performances. A G*Power (version 3.1.9.7) analysis determined the required sample size, adopting a 95% confidence level, 90% test power, and an effect size of 0.25. Validity assessments were conducted using Bland-Altman plots and ordinary least products (OLP) regression analysis, while reliability was evaluated through intraclass correlation coefficient (ICC), coefficient of variation (CV), standard error of measurement (SEM), and smallest detectable change (SDC) analyses. DeepSport showed excellent reliability in CMJ and SJ tests with ICC values > 0.90, and CV ranged between 2.12% and 4.95%. Results were consistent with OptoJump, showing no significant differences according to t-test results (p > 0.05). Bland–Altman analyses indicated no systematic bias and random distribution. These findings confirm that both DeepSport and OptoJump devices demonstrate high reliability and consistency, suggesting their validity and reliability for use in athlete performance assessments by coaches and athletes. Full article

Background/Objectives: Vertical jump is considered a reliable and valid method of assessing the level of muscular power and coordination across one’s lifespan. The main aim of the present study was to establish sex- and age-normative data for vertical jump outcomes in pre-school children. Methods: We recruited 411 boys and girls aged 3−6 years from four major cities in Croatia and Slovenia. Vertical jump was assessed with two tests: countermovement jump (CMJ) without and with arm swing using a reliable and valid Optojump measuring platform. Data were presented for the 5th, 15th, 25th, 50th (median), 75th, 90th, and 95th percentile. Results: No significant differences were observed in multiple vertical jump outcomes between boys and girls. The mean values for CMJ without and with arm swing between boys and girls were as follows: contact time (1.4 vs. 1.4 s/1.8 vs. 1.7 s), flight time (0.32 vs. 0.31 s/0.33 vs. 0.32), height (12.3 vs. 12.2 cm/13.0 vs. 12.5 cm), power (9.4 vs. 9.5 W/kg/9.3 vs. 9.1 W/kg), pace (0.7 vs. 0.7 steps/s/0.6 vs. 0.6 steps/s), reactive strength index (RSI; 0.10 vs. 0.09 m/s/0.08 vs. 0.08 m/s), and verticality (2.5 vs. 2.3/1.9 vs. 1.9). A gradual increase in all measures according to ‘age’ was observed (p for trend < 0.05). No significant ‘sex*age’ interaction was observed (p > 0.05). Conclusions: This is one of the first studies to provide sex- and age-normative data for complete vertical jump outcomes in pre-school children. These data will serve as an avenue for monitoring and tracking motor development in this sensitive period. Full article

The main goal of this study was to determine whether the type of spike can influence the final sprint result by comparing step by step the kinematics of four 50-m sprints. Twelve well-trained junior sprinters (ages 17–19) from the Polish National Team (ranging from 100 to 400 m) participated in the study, with personal bests in the 100-m sprint of 10.70 ± 0.19 s. The OptoJump Next-Microgate sensor measurement system (Optojump, Bolzano, Italy) was used to measure the essential kinematic sprinting variables. Following the sprint distance, photocells were placed on the track at the start, at 10 m, at 20 m, at 30 m, and at the finish (50 m). Fifty-meter sprints were completed alternately, two with classic and two with the carbon-plated spikes. For every sprinter, the order in which the spikes were chosen was randomized. To better understand the problem of variability in kinematic parameters, in addition to the actual statistics, the profile analysis process was applied. The analysis of the four 50 m sprints did not show significant differences between the kinematic parameters considering runs in both the classic Nike and carbon-plated Nike ZoomX Flymax spikes. It may be suggested that spikes’ sole bending stiffness may not affect short-distance (up to 50–60 m) sprinting performance. From a practical point of view, training focused on maximum speed development can be carried out with both classic and carbon-plated spikes. Finally, our experiment can guide the preparation of a research methodology that assesses the effect of carbon-plated spikes on prolonged sprinting, e.g., 200–400 m. Full article

The purpose was to design and validate a battery of physical tests, called EFEPD-1.0, adapted to assess functionality in people with disabilities. In addition, we sought to analyze the validity and reliability of this battery both for the total group and differentiated by sex. A total of 43 adults with disabilities (32 women and 11 men) participated (57.11 ± 10.12 years). The battery was composed of five blocks of functionality: neuromuscular, combined actions, acceleration, balance, and cardiovascular. The neuromuscular functionality was measured by the vertical and horizontal jump test using the optical system (Opto Jump Next^®, Microgate, Bolzano, Italy) as well as the Hand Grip (HG) test using a (5030J1, Jamar^®, Sammons Preston, Inc, Nottinghamshire, UK) hand dynamometer. The combined actions and balance functionality were assessed with the Time Up and Go (TUG) test, the 30 s Chair Stand (30CTS) test, and the One-Leg Stance (OLS) test measured by a manual stopwatch (HS-80TW-1EF, Casio^®, Tokyo, Japan). The acceleration functionality was evaluated through 20 m sprints and the 505 change of direction (COD505) test, using the (Microgate, Witty^®, Bolzano, Italy) photocell system. The cardiovascular functionality was evaluated with the Six-Minute Walking Test (6MWT), where heart rate was monitored using the (Polar Team Sport System^®, Polar Electro Oy, Kempele, Finland), and additional walking mechanics were recorded with Stryd (Stryd Everest 12 Firmware 1.18 Software 3, Stryd Inc., Boulder, CO, USA). The results showed that the intraclass correlation coefficients (ICCs) ranged from moderate to almost perfect (ICC = 0.65–0.98) between test repetitions. Some tests could significantly differentiate (p < 0.05) men and women, highlighting better neuromuscular capacity in men and better balance in women. The correlations between tests showed significant convergent validity. The Evaluation of Functionality in the Disabled Population (EFEPD-1.0) battery not only consistently measures functional capacities in people with disabilities, but it can also discriminate between different subgroups within this population. Full article

Background/objectives: The study aims to investigate potential differences in vertical jump performance between elite basketball and volleyball players before and after a standard training session, in comparison to a control group from the general population. The analysis focuses on the influence of selected gene polymorphisms that may contribute to variations in the assessed performance parameters. Aims: The aim was to investigate the influence of ACE (rs4646994), ACTN3 (rs1815739), PPARA rs4253778, HIF1A (rs11549465), and AMPD1 (rs17602729) genes polymorphisms on the combined effects of post-activation potentiation (PAP), post-activation performance enhancement (PAPE), and general adaptation syndrome (GAS), as reflected in vertical jump performance, in elite basketball and volleyball players compared to a control group from the general population. Methods: The effects of PAP at the beginning of the training load (acute exercise), and the combined influences of PAPE and GAS following the training load were evaluated using parameters measured by the OptoJump Next^® system (Microgate, Bolzano, Italy). Results: A statistically significant (h, p < 0.05) negative effect of the CT genotype of the AMPD1 gene on jump height was observed in the group of athletes. The CT genotype of the AMPD1 gene negatively impacted on PAPE and GAS adaptive responses (ΔP, Δh, p < 0.001) also in the control group. A positive effect on the power during the active phase of the vertical jump was identified for the II genotype of the ACE gene and the Pro/Ser genotype of the HIF1A gene, both exclusively in the control group (ΔP, p < 0.05). Conclusion: Our findings demonstrate that different gene polymorphisms exert variable influences on the combined effects of PAPE and GAS, as reflected in vertical jump parameters, depending on the participants’ level of training adaptation. Full article

Background: This paper presents research on the comparison and evaluation of lower limb power, movement, position on the court, and effectiveness in the players of men’s volleyball. The study involved professional players in the first division of a men’s volleyball team. The main aim of this paper was to show the correlation between lower limb power, movement, position on the pitch, and volleyball efficiency. Methods: The authors presented basic somatic characteristics of anthropology metrics, advanced research results obtained with the Optojump measuring system, players’ results statistics obtained with the Data Volley software (v.4.2024.01), and by applying scientific statistical methods and graphics interpretation. Results: The analyses with the Kruskal-Wallis test showed statistically significant differences in all the variables studied. Flight time (TF, H = 122.967; p < 0.001.) was the shortest for the players in the libero position, then the setter, attacker, middle and longest flight time was shown by the receiving players. The height of the jumps (JH, H = 123.018; p < 0.001) was the highest for receiving and mid players, and then attackers and setters, and the lowest jumps were recorded by libero players. The highest power of lower limbs (P, H = 20.392; p < 0.001) was characteristic for receivers, setters, mid-players and, curiously, libero achieved a better result than attackers. Conclusions: The analysis shows that the power of the lower extremities in volleyball players is associated with the function they perform on the court. Full article

This study examines the influence of fatigue and defensive pressure on the kinematic parameters of the three-point jump shot in basketball. Fourteen male collegiate basketball players (age: 21 ± 3 years old, body height: 186.35 ± 7.02 cm, body mass: 82.20 ± 10.99) participated in the study. Each participant performed three-point jump shots under four conditions: without defense, with defense, without defense after a fatigue protocol, and with defense after a fatigue protocol. Kinematic data were collected using the Xsens MVN inertial suit system and the OptoJump Next system. The analysis focused on various parameters including jump height, center of mass, release height, shoulder angle, and segment velocities. The repeated-measures ANOVA was used to observe the differences between each shot condition (fatigue, defense). Results indicated significant changes in the kinematic parameters due to both fatigue and defensive pressure. Fatigue notably changed shooting performance, affecting jump height and release mechanics. The defensive pressure altered shooting technique, leading to quicker ball release and higher release points. These findings highlight the importance of incorporating fatigue and defensive scenarios in training, suggesting that coaches develop more targeted training plans to improve performance under conditions of fatigue and defensive pressure. Full article